The knowledge of the effects of sunlight on the eyes and protective behaviors were studied in an adolescent population. A group of 652 systematically sampled students aged between 13 and 17 years was surveyed with a standardized questionnaire in Brisbane, Australia in October-November, 1995. Survey data on the knowledge of sunlight effects on the eyes, ultraviolet light, eye and body protection as well as risk factors for ultraviolet (UV) exposure were relatively ranked and totalled to give overall scores. Of the 652 subjects, 330 (51%) were female. Most subjects (568 or 88%) were aged between 15 and 16 years. Overall, this group of subjects demonstrated a moderate level of knowledge with respect to UV, sunlight and the eyes. The knowledge of the effects of sunlight and body protection was higher than the knowledge of the effects of sunlight and eye protection. Almost three-quarters (462 or 71%) of the subjects owned a pair of sunglasses. The mean age at which subjects started to wear sunglasses was 10.4 years. However, most subjects (528 or 81%) only wore sunglasses occasionally or not at all. The reported frequency of wearing sunglasses was significantly related to personal, family and peer attitudes to such use, but not to media advertizing. Assessment of adolescent knowledge is important in the formulation of health promotion strategies designed to prevent excessive UV exposure at this young age.